VZG Statement on NAS Panel

Von Storch, Zorita and Gonzalez-Raucen have issued the following statement on the NAS Panel Report:

We welcome the National Research Council’s Report, which clarifies that the discussion about the technical qualities of the hockeystick-methodology is insignificant for the overall conclusion that the presently ongoing warming is likely related to elevated greenhouse gas concentrations in the atmosphere. We are pleased to read that the NRC shares our view that the methodology behind the hockeystick is questionable. We stick to our view that the methodology was not sufficiently described when published and independently tested thereafter.

1) We welcome the conclusion of the analysis by the NRC committee, which separates between two issues, namely firstly the claim that the last few decades (the last decade, the year 1998) were unprecedented in their warmth compared to a previous time horizon, and secondly the certainty we place into the published estimates of temperature variations in the past 1000-2000 years.

2) The assessment that the last few decades have exhibit a warming likely beyond the range of natural variations has been made on a variety of scientific findings, of which the Mann et al study was possibly the most publicly “sold” one, but other studies have provided better evidence (detection and attribution studies).

3) We share the assessment of the NRC committee that the evidence for unprecedented warming of a single decade or even a single year in times prior to 1500, or so, is stretching the scientific evidence too far. However, this was the key claim made in the contested 1998-nature and 1999-GRL-papers by Mann et al.

4) With respect to methods, the committee is showing reservations concerning the methodology of Mann et al.. The committee notes explicitly on pages 91 and 111 that the method has no validation (CE) skill significantly different from zero. In the past, however, it has always been claimed that the method has a significant nonzero validation skill. Methods without a validation skill are usually considered useless.

5) Other independent efforts (e.g., inversion of borehole temperatures) to reconstruct past temperatures find different temperature ranges albeit qualitative agreement. These quantitative differences underline the methodological limitation of the Mann et al approach, which are described in the sections 9 and 11 of the NRC report.

6) We welcome the major conclusion of the report that further scientific efforts are needed to sort out a variety of problems with respect to methods and data ; also the uncertainty must be assessed in a more objective manner. Thus, the public perception that the hockeystick as truthfully describing the temperature history was definitely false.

7) We find it disappointing that the method of Mann et al. was not sufficiently described in the original publication, and thus not peer-reviewed prior to publication, and that no serious efforts were made to allow independent researchers to check the performance of the methods and of the data used.

The assessment that the last few decades have exhibit a warming likely beyond the range of natural variations has been made on a variety of scientific findings, of which the Mann et al study was possibly the most publicly “sold” one, but other studies have provided better evidence (detection and attribution studies).

Name those better studies. I’ll name you some good studies that don’t.

Other independent efforts (e.g., inversion of borehole temperatures) to reconstruct past temperatures find different temperature ranges albeit qualitative agreement. These quantitative differences underline the methodological limitation of the Mann et al approach, which are described in the sections 9 and 11 of the NRC report.

Which independent efforts? Are they independent when they share the same flawed data, many of the same flawed methods and many of the same flawed authors?

Again we have an appeal to consistency, as if this meant anything.

“Consistency requires you to be as ignorant today as you were a year ago” – Bernard Berenson

No way boreholes can tell you if present tempeatures are higher now than 1000 years ago. They just don’t have sufficient resolution. Anyway John was missing that pointing to these other efforts was to point out that the results, though similar in kind, were different in detail and that thus trying to say something about a year or decade is premature at best.

VZG wrote that, “other studies have provided better evidence (detection and attribution studies) [that] the last few decades have exhibit[ed] a warming likely beyond the range of natural variations…”

What studies have provided what evidence? The highest precision ice-core study I’ve seen (Fischer, ea (1999) “Ice Core Records of Atmospheric CO2 Around the Last Three Glacial Terminations” Science 283, 1712-1714) has a resolution of +/- 200 years. I don’t think there is any evidence anywhere that shows 20th century warming was “beyond the range of natural variations.”

Pat, since they mention “detection & attribution studies,” I think they are referring to the modelling studies that claim you can’t reproduce the recent temp history w/o high-CO2 forcing (i.e. w/ known “natural” factors alone).

Actually, the Vostok ice core and other (more regional evidence like from Alaska and Yukon with forests far beyond the current latitudes) show that the previous interglacial (the Eemian) was in global average several degrees C warmer than today’s temperatures. Without much help of CO2…

Thanks Armand, but if that’s what they mean, namely physical models that are at least an order of magnitude too crude to resolve a 4 W/m^2 energy flux, then they literally don’t know what they’re talking about.

Armand, they’re scientists, not politicians, and they’re talking about science not politics. GCM models have produced zero detection and attribution evidence. If they want to be politicians, let them stand for election. Everyone expects stretched truths, then, and doesn’t resent them so much. I’m not saying that VZG are lying. I’m saying that if they’re making claims about GCMs then their claims are scientifically insupportable. They ought to know that. So why are they, as scientists, saying otherwise? In my papers and seminars, I don’t get to claim what I can’t support. Why do they?

re 0.
Sure, They also popint to high-latitude ice bore data, glacial length data (also time restricted), glacial isotope data (iffy as a temp proxy in tropical glaciers, but asa combined temp/precip proxu clearly showing a 20th centruy climae anomaly) and several kinds of qualitative glacier data that supports the outlne of 20th century either right at the upper limit or, for some of the, clrealy anomalous.

John’s claim that they were all dependent is simply absurd.

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